When playing 4/8 at 60 bpm will the rhythm or my foot tapping should be twice as fast compared to 4/4 at 60 bpm? If that's the case then does that mean bpm has been changed to 120? But I have read somewhere that beats normally remain constant in entire piece of music.

Please explain in simple words. I have read other answers here in this forum but couldn't understand exactly.

9 Answers 9


First of all tempo is not affected by time signature, however what gets the beat does change as the time signature changes so this is the source of much of the confusion.

It depends on how you are using the terminology BPM as currently it is very ambiguous. Most of the time when people reference BPM,they reference quarter notes as the beat which may not actually be what the time signature signifies implies as the beat as seen here:

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In this the tempo is exactly the same, but if you were to play them the 4/8 would sound faster because the eigth note's duration is half of the quarter note's duration which makes sense because 4 quarter notes reduce to 2 eigth notes so the 4/8 measure is half the length of the 4/4.

If you truly meant that the beat is played 60 times a minute then you would get:

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In this the tempo is different, but if you were to play them they would sound exactly the same speed because both measures take the same amount of time at their respective tempos.

So depending on what you are saying gets the beat in each BPM, your answer could be yes or no because of ambiguity.


No, the tempo doesn't change based on the time signature. Time signature and tempo are two different things. Time signatures tell you how many beats there are in a measure and how a beat is notated (4/4 = four beats in a measure of quarter notes).

A tempo (BPM) tells you how fast that beat goes by (120 BPM = 1 beat per 0.5 second).

4/8 means you have four beats counted as eighth notes, each foot tap is an eighth note (a quarter note now takes 2 beats).

  • This looks like the best answer so far even though it leaves out the direct answer of "No". Since 60 bpm is the tempo for both the hypothetical 4/4 and 4/8 time signatures, they would both be played at the same tempo. Commented Sep 5, 2015 at 9:08
  • @ToddWilcox - this would presume that a beat is both a crotchet and a quaver. How can that be?
    – Tim
    Commented Sep 5, 2015 at 9:37
  • I guess it depends on whether we are answering the question in the title or the body of the question. The tempo does not change. The rhythm sort of does, assuming you consider notes per minute as part of rhythm, instead of viewing rhythm as merely the pattern played regardless of speed. Commented Sep 5, 2015 at 17:42

I would just offer an opinion contrary to those already. I would say that the Time Signature really has nothing to do with the tempo of the piece.

In essence all a Time Signature aims to do is to tell you how many pulses / beats there is in a bar and also what the beats consist of.

Now there is a tendency in music to want to play music that is written in smaller divisions of notes faster and the converse is also true that people often want to play 2/2 time signatures slower.

This is off course really incorrect. A piece in 2/2 Time can be played fast just as much as a Time Signature like 4/8 can be played slow.

You also sometimes get Organ pieces that is almost only semiquavers and demisemiquaver but since the tempo is 60 bpm the music is still very slow.


It depends on how the unit beat is defined for that piece or that tempo. Contrary to what you have read, tempos can change very often within one piece of music (the obvious exception being the pop/dance/club music all we seem to hear on the radio).

If a piece of music is in 4/4 time at 60bpm, then you know that there will be four beats per measure (top number) and the quarter note will be the symbol that defines the unit beat (bottom number). You also know that one quarter note (or pulse) will occur at a rate of 60 beats per minute.

Now, if a piece of music is in 4/8 time at 60bpm, then you know that there will be four beats per measure (top number) and the eighth note will be the symbol that defines the unit beat (bottom number). Here, the eighth note pulse will occur at a rate of 60 beats per minute.

In 4/4 time, regular 8th notes are 1/2 of a beat, and therefore occur twice as often. It is dangerous to think of this as 120bpm because the unit beat is the quarter note, not the eighth note, and is kept at 60.

In 4/8 time, regular quarter notes are now worth twice the beat, and therefore occur half as often. It is dangerous to think of this as 30bpm because the unit beat is the eighth note, not the quarter note, and is kept at 60.

As others have suggested, tempo and time signature can be completely independent of one another. Depending on how you notate the music, your 4/8 could be slower than your 4/4, or in another plane of existence altogether.

So, my answer is this: it depends on how you notate your music.


The correct answer to the question that was asked is "no." Music written in 4/8 will not "sound faster" at 60bpm than music written in 4/4...as long as you're defining 60bpm as [quarter note]=60.

what will change is how fast you read through the written measures.


No, in answer to the question. The clue is in b.p.m. It will absolutely depend on what that beat is. That's designated in the bottom number of the time sig. Whatever that is will be a 'beat'. Usually 4, as in a quarter note (crotchet), this becomes one a second at 60 bpm. If that bottom number is 8 (quavers), and the bpm. is 6o, then the beats - quavers - are still 60 per minute - one a second. Yes, it would look twice as fast when comparing, but they wouldn't normally both exist in the same piece. The time sig. would remain, and the notes would be half as long, to speed up the tune to twice the tempo.


As simple as can be:

  • Basically - a lot of notes doesn't necessarily mean 'fast' tempo.
  • The 'Time-signature' is just the indicator for the basic 'pulse' of your song not for the speed of the melody or any other element!
  • The 'Tempo' of this basic beat is by default measured in quarter-notes - BPM.
  • Traditionally the 'time-signature' is also measured and indicated in quarter-notes (common-time).
  • When it comes to 'smaller' signatures (n/8) we want to indicate a different perception of the basic pulse, although we tend to group these eights back together (when we e.g. raise the tempo) just to fit into our basic perception of a basic '(quarter-note)-pulse' -> (e.g. 6/8 into 2 groups of 3 eights)

4/8 has - you already guessed it - the same tempo as 2/4:

As BPM counts the beats in quarter-notes you have to bring both signatures onto the same level in order to be able to compare their 'tempo'.

Now, they are - 4/4 vs. 2/4 - so 'SAME' Tempo - one beat per second at 60 BPM.

But - you just might wanna express your intent to play the tune more 'agitato' and fast (double time) and even write out all the quarter notes as eights. The Tempo (bpm) would stay the same! You are just playing in double time. And of course you could - additionally - indicate this by using a n/8 signature!

e.g. you could use a 8/8 instead of a 4/4 - same Tempo - but you convey another feeling of the basic pulse of your song!

If you want the reversed effect you would write an 'alla breve' signature or 2/2 or 4/2.

The time-signature essentially indicates the basic 'PULSE' of your composition that e.g. a conductor is most likely to convey to the orchestra. Your foot is your conductor and shows that intent to your body ;-) and this should also be reflected in your score.

If you want to have the basic beat of the BPM signature (quarter by default) understood differently you have to explicitly write e.g.

  • [symbol of an eighth-note] = 60 BPM
  • [symbol of a dotted quarter-note] = 60 BPM

For example if you had this already mentioned 6/8 and you wanted the pulse to beat two times per measure/bar (3 eights) and last exactly for one second - almost like triplets in a common-time...

A Viennese Waltz, although giving a very clear message of a 3/4 quarter-note pulse, has a very strong impulse on the 1st beat, and a conductor will most likely convey this to the orchestra by beating once on every bar. But as soon as a ritardando comes along he will definitely go back to 3 beats.

So Tempo-signature, Time-signature and other annotations by the composer always go together to convey a good understanding of the intended tempo, pulse and feeling of the composition!

When headed to some destination you can make a lot of small but fast steps or a few slow but big steps. Although your body would convey a totally different message to someone looking at your (stressed, relaxed or whatever) gestures - you would reach your destination at the same time...

  • 2
    Default may be crotchet (quarter note), as that is by far the most common denomination, but when the bottom no. is 2, then default becomes minim, and when it's 8, as in 6/8, the default becomes a dotted crotchet .
    – Tim
    Commented Sep 6, 2015 at 9:42
  • @Tim: That's why I wrote -> 'If you want to have the basic beat of the BPM signature (quarter by default) understood differently... ' -You must have overlooked it... ;-) -> We can delete our comments if you like...
    – mramosch
    Commented Sep 6, 2015 at 12:15

Actually it would feel slower. The reason is that the beats are eighths now. The actual tempo stays the same but it feels slower.

Now as a good example take 2/2 and 4/4. These are 2 equivalent time signatures. The beats however are different. So 2/2 feels faster than 4/4. Now if you play the 2/2 twice as slow it is going to feel the same as if you did it in 4/4.

Well if you play the 4/8 twice as fast it is going to feel like 2/4 and that feels very similar to 4/4.

  • But presumably the metronome marking for the 4/8 will say that the eighth note equals 60 beats per measure. So I disagree. Commented Sep 5, 2015 at 6:10
  • 1
    This isn't correct. 2/2 has 2 minims per bar, 4/4 has 4 crotchets. Both bars will last exactly the same time, given the appropriate tempo mark. You may be confusing time sigs with fractions. They look similar, but do not mean the same.
    – Tim
    Commented Sep 5, 2015 at 7:18
  • No. At the same tempo 2/2 will feel faster because now the half note lasts as long as the quarter note in 4/4. This goes on to wholes lasting as long as halves, quarters lasting as long as eighths etc. Also at the same tempo 4/8 will feel slower because now it is the eighths at 60 beats per minute not quarters.
    – Caters
    Commented Sep 5, 2015 at 18:58

4/8 and 4/4 are exactly the same speed for your foot at 60 bpm, with your foot tapping once per second, just that it taps once per eighth in the first case and once per quarter in the second case.

4/8, however, would be quite an unusual meter: it is more common to have 2/4. One reason is that basically uses x/8 when there is a grouping structure to the notes more than an accent structure. The notation can nicely express this structure by employing beaming. 4/4 has a strong accent on 1 and a weaker one on 3. 6/8 has a 2+2+2 or a 3+3 structure. The only grouping substructures of 4/8 without singular groups are 2+2 and 4.

2+2 would be a rather march-like very strict pattern but that is already succinctly expressed by 2/4 which uses the same beaming pattern. So that just leaves the "4" option where everything is running in non-substructured groups of 4 beats. Not impossible, but rather uncommon to single out in that manner.

Do you have actual music underlying your question, or is that more of a theoretical musing?

  • 2
    6/8 will be 3+3, not 2+2+2. That's the whole nature of 6/8.
    – Tim
    Commented Sep 5, 2015 at 9:28

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